The assays that have been applied to measure the latent reservoir in studies performed to date have been imprecise, in some cases non-specific, and in all cases near the threshold of detection for specimens obtained from subjects effectively treated with antiretroviral therapy. A successful Collaboratory effort to eradicate the latent reservoir must have assays available that can reliably quantify this reservoir and measure reductions in its size. In Project 4.1, superior assays in development for integrated viral DNA and for viral infectivity will be refined and validated for HIV, and then applied to both the SIV and RT-SHIV macaque models. They will then be applied to in vitro models of latency and to cells and tissues obtained from infected macaques and HIV-infected study subjects, as part of other Collaboratory research projects. Microfluidic applications to these assays will address the question of the representativeness of the proviral reservoir for replication-competent virus and try to explain some of the mechanisms for replication in competent virus. The presence of HIV DNA and infectivity in blood macrophages, as a potential reservoir, will also be examined. These studies to improve measurements of the latent reservoir and interventions to purge it will involve close interactions and the exchange of methods and materials with several of the project and core Collaboratory investigators.